AN APPLICATION OF THE PAIRED FEEDING METHOD TO THE QUANTITATIVE ESTIMATION OF THE RELATIVE VITAMIN B CONTENTS OF FOODS AND ARTIFICIAL CONCENTRATES

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Abstract
A method has been developed for measuring the relative content of vitamin B in different materials. The measurement defining this content is the minimum percentage of the material in question required for maximum growth. The method is an application of paired feeding, in which both rats of each pair receive the same amount of the same basal diet, complete in all respects except vitamin B, which is furnished by a definite percentage of the material under test. One rat in each pair receives a vitamin B supplement, and if in a number of pairs the rat receiving the supplement gains faster than its control then the ration may be said to be deficient in vitamin B. The desired critical percentage of test material is found by testing various percentages in this way. The unique advantage of the method over all others thus far proposed is that the entire food intake of the experimental rats is under complete control, so that all comparisons of growth rates are made only between animals receiving the same amount of food. Hence, differences in growth can be traced more directly to differences in vitamin intake. The critical percentages obtained for corn and wheat are, respectively, between 40 and 45, and between 50 and 55, indicating a smaller concentration of vitamin B in wheat. Some indications were obtained that the requirements for vitamin B in a balanced ration become less the greater the concentration of protein. The appetite-stimulating effect of vitamin B appears even when the vitamin B content of a ration already adequate in this respect is increased.

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